ERP is a protocol for redundancy and loop prevention in an Ethernet (registered trademark) ring using Ether OAM (Operation Administration and Maintenance) (see Non Patent Literature 1).
ERP supporting only wired communication is known. In this ERP supporting only wired communication, a communication path is switched on condition that a link is down.
Further, Patent Literature 1 discloses a technique in which, when a difference between an uplink speed and a downlink speed is equal to or greater than a threshold between wireless communication apparatuses, it is determined whether a communication failure has occurred in wireless communication in any of communication directions, path cost is changed and recalculated using a line speed for the wireless communication, on which the determination of the communication direction is made, and STP (Spanning Tree Protocol) path control is performed based on the path cost.